1. Field of the Invention
The present invention relates to a portable device, carried by a user, for an electronic key system.
2. Description of the Related Art
Conventionally, a known electronic key system checks the ID of the user, by radio communication between the portable device of the user and an electronic device, and performs security functions of locking/unlocking a door. Especially, the electronic key system for an automobile, in which the engine is permitted to start based on the ID check between the portable device and the on-vehicle electronic device, finds practical applications to improve the anti-theft effect.
In the electronic key system of this type, in preparation for the power failure of the battery of the portable device, an emergency key providing a mechanical key (key plate) is encased in a housing formed in the body of the portable device.
Further, in the portable device of the conventional electronic key system, a lock mechanism is constructed in the body to prevent the emergency key from easily coming off from the housing formed in the body.
As shown in FIGS. 8A, 8B, for example, a body 103 of a portable device 101 includes a lock mechanism having a manually slidable slide member 105 and a spring 107 adapted urge the slide member 105 in a predetermined direction. A protrusion 105a formed on the side of the slide member 105 far from the spring 107 is fitted in the engaging groove 111a of an emergency key 111 inserted in the housing 109 of the body 103. In this way, the emergency key 111 is prevented from coming off from the housing 109. In this example of the configuration, the slide member 105 is slid against the urging force of the spring 107 (i.e. leftward in FIGS. 8A, 8B), the protrusion 105a of the slide member 105 comes off from the engaging groove 111a, and the emergency key 111 can be pulled off from the housing 109 of the body 103. FIG. 8A is a front view of the portable device 101 and FIG. 8B a left side view thereof (Refer to Japanese Patent Publication No. 2002-32284 (FIG. 3)).
As described above, in the conventional portable device 101, the operation of mounting or demounting the emergency key 111 (specifically, the operation of fitting or removing the protrusion 105a in and from the engaging groove 111a) can be performed by sliding the whole slide member 105. In this case, a space for sliding the slide member 105 is formed on the body 103 of the portable device 101. For this purpose, a large space is required due to the fact that the whole slide member 105 is slid, thereby posing a stumbling block to reducing the size of the portable device.